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Neighbors are shocked as police search the Vermont home of Nathan Carman, who was lost at sea for more than a week. His mother, with whom he set sail, is missing and presumed dead. And sources say he is being considered a person of interest in his grandfather's 2013 murder. (Published Wednesday, Sept. 28, 2016)

A man rescued after spending a week at sea says he had nothing to do with his grandfather's 2013 unsolved slaying and didn't harm his missing mother.

Twenty-two-year-old Nathan Carman told The Associated Press on Wednesday that the fishing boat he was in with his mother sank within a matter of minutes. Carman was rescued Sunday. His mother, Linda Carman, 54, of Connecticut, is missing and presumed dead.

Carman told the AP by telephone that after water began pouring into his boat, he saw his mother in the cockpit. He said he grabbed survival gear, then looked back and she was gone.

He said he was like a son to his grandfather, who was slain in Connecticut.

Carman was lost at sea for more than a week before he was found alive on a life raft Sunday by a Chinese freighter about 100 nautical miles south of Martha's Vineyard.

Police searched Carman's Vermont home earlier this week, removing an Internet modem, a SIM card and a letter he wrote. An affidavit shows that authorities believed they would find evidence relating to the presumed death of his mother.

"I saw a lot of lights going around the building and in and out of the door," said neighbor Jessica Boudreau of the search. "I think it's crazy that he lost his mother on such a small boat and he couldn't get her on and find her."

Neighbor Mike Iozzi spoke with Carman when he was repairing the boat, and he said he was all business, showing little emotion.

"Strange," Iozzi said. "Strange."

Iozzi went on to say Carman spent most of that Saturday working on his boat. At one point, Iozzi said his friend asked Carman if he wanted something to eat.

"When Nancy offered him a sandwich, a meatball sandwich, he said he didn't want any bread," he said. "Not that that is so strange, but then she said, 'how about a water?' 'I don't drink water.' Just thought that was a little strange"

"Myself and my mom were fishing on Block Canyon and there was a funny noise in the engine compartment," Carman said to rescue crews in audio released by the Coast Guard. "I looked and saw a lot of water."

Carman returned to dry land Tuesday. He faced more questions from the Coast Guard, then went back to the Vermont home with his father. The search warrant was executed the night before.

Court paperwork released along with the search warrant shows that Alfred E. Bucco, a lieutenant with the South Kingstown Police Department in Rhode Island, believed "evidence relating to the crime of RIGL 46-22-9.3 {Operating so as to endanger, resulting in death} will be located inside Nathan's residence."

Authorities have not named Carman a suspect in his mother's disappearance. The search has been called off and she is presumed dead.

Neighbors call Carman quiet and say he is rebuilding the farm home.

Back in December of 2013, Carman's maternal grandfather, real estate developer John Chakalos, was shot to death at his home in Windsor, Connecticut. His killing has not been solved.

A source close to the investigation told NBC Connecticut that Nathan Carman is being called a person of interest in the death. At the time, he was living one town away in Bloomfield.